Question
When I turn my water supply on one zone on my Toro system stays on, even when I have my system on the off position.  I am new to the system and moved into the house so not sure what the problem is.  Maybe the valve?

Answer
Might be.  Check the flow control on the valve, which is the largest knob on top.  It should be about halfway open.  If this doesnt solve, you may need to dissemble the valve and check the interior parts for wear and damage.  Follow this link for instructions:

http://www.irrigationtutorials.com/faq/repair-valve.htm